DHCP frantic requests with wrong expires-after value

RouterOS General
1

SERVER SIDE

doas grep lease /etc/dhcpd.conf
default-lease-time 3600;
max-lease-time 3600;

LOG

Repeated every 15 seconds:

May 24 19:58:34 dhcpd[91838]: DHCPREQUEST for 192.168.1.31 from 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPACK on 192.168.1.31 to 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPDISCOVER from 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPOFFER on 192.168.1.31 to 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPDISCOVER from 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPOFFER on 192.168.1.31 to 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPREQUEST for 192.168.1.31 from 48:a9:8a:9c:1d:4b via vether0
May 24 19:58:34 dhcpd[91838]: DHCPACK on 192.168.1.31 to 48:a9:8a:9c:1d:4b via vether0

MIKROTIK SIDE

> /ip/dhcp-client/print
Columns: INTERFACE, USE-PEER-DNS, ADD-DEFAULT-ROUTE, STATUS, ADDRESS
# INTERFACE    USE-PEER-DNS  ADD-DEFAULT-ROUTE  STATUS  ADDRESS
;;; defconf
0 bridgeLocal  yes           yes                error   192.168.1.31/24

> /ip/dhcp-client/print detail
Flags: X - disabled, I - invalid, D - dynamic
0   ;;; defconf
interface=bridgeLocal add-default-route=yes default-route-distance=1 use-peer-dns=yes use-peer-ntp=no dhcp-options=hostname,clientid status=error address=192.168.1.31/24 gateway=192.168.1.1 dhcp-server=192.168.1.3 primary-dns=192.168.1.3 secondary-dns=192.168.1.1 expires-after=2d21h33m18s

What I see

  • the DHCP server sets a lease time of 3600 seconds;
  • the MIKROTIK DHCP client status reports an unspecified error;
  • the MIKROTIK DHCP client says it received a lease time of neary 3 days;
  • the MIKROTIK client hits the DHCP server every 15 seconds.

Reference

/system/routerboard/print
routerboard: yes
board-name: hAP ax^2
model: C52iG-5HaxD2HaxD
serial-number: HEB08ZETYA3
firmware-type: ipq6000
factory-firmware: 7.6
current-firmware: 7.15
upgrade-firmware: 7.15

The DHCP server is OpenBSD, and its lease time has been verified using various tools: dhcpdump, dhcpcd, nmap and nagios.

This device is managed by CAPsMAN. Other DHCP-enabled non-CAP MT devices do not behave like this.

Edited to show latest values.
export.rsc (2.83 KB)

v7.14.3 [stable] is released!
2

Did you change the max lease time between the MikroTik asking for the lease and now that you see this problem?

3

NO

4

https://download.mikrotik.com/routeros/7.15/CHANGELOG

*) defconf - do not override default DHCP server lease time;

I see…

Currently in the process of upgrading and testing. Will report back.

5

Updated.


> ssh 192.168.1.31 '/system/routerboard/print'
routerboard: yes
board-name: hAP ax^2
model: C52iG-5HaxD2HaxD
serial-number: HEB08ZETYA3
firmware-type: ipq6000
factory-firmware: 7.6
current-firmware: 7.15
upgrade-firmware: 7.15

Query:


ssh 192.168.1.31 ‘/ip/dhcp-client/print detail’
Flags: X - disabled, I - invalid, D - dynamic
0 ;;; defconf
interface=bridgeLocal add-default-route=yes default-route-distance=1
use-peer-dns=yes use-peer-ntp=no dhcp-options=hostname,clientid
status=error address=192.168.1.31/24 gateway=192.168.1.1
dhcp-server=192.168.1.3 primary-dns=192.168.1.3
secondary-dns=192.168.1.1 expires-after=7m58s

I see the expires-after is nearing completion.
I am waiting for the expiration date to see what happens.
I also see “status=error”, also present in the previous report.

6

The “expires-after” parameter … keeps increasing???


ssh 192.168.1.31 ‘/ip/dhcp-client/print detail’
Flags: X - disabled, I - invalid, D - dynamic
0 ;;; defconf
interface=bridgeLocal add-default-route=yes default-route-distance=1
use-peer-dns=yes use-peer-ntp=no dhcp-options=hostname,clientid
status=error address=192.168.1.31/24 gateway=192.168.1.1
dhcp-server=192.168.1.3 primary-dns=192.168.1.3
secondary-dns=192.168.1.1 expires-after=14m13s

…

ssh 192.168.1.31 ‘/ip/dhcp-client/print detail’
Flags: X - disabled, I - invalid, D - dynamic
0 ;;; defconf
interface=bridgeLocal add-default-route=yes default-route-distance=1
use-peer-dns=yes use-peer-ntp=no dhcp-options=hostname,clientid
status=error address=192.168.1.31/24 gateway=192.168.1.1
dhcp-server=192.168.1.3 primary-dns=192.168.1.3
secondary-dns=192.168.1.1 expires-after=20m36s

This is a bug. Please correct the programming error.

7

Have you checked out the new v7.15 that dropped today? If you’re still having trouble and since this is just a user forum, I suggest sending in a bug report to ‘support@mikrotik.com’.

8

Yes, I updated.

Bug report sent, although it seems they are reading this.

9

This device is managed by CAPsMAN.

Other devices with DHCP enabled do not behave like this.